There's no need to install a software in the customer's PC. The ISP may offer a transparent filtering.

Netfilter Service may be offered to ISP clients through a configuration solution with the following components:

• NetFilter ISP Server: Performs filtering and administration functions, and shall be installed by ISP at its own site.
  
• Software NetFilter ISP:
  . Internet Access filtering
  . ISP Administration Kit
  
  
• NetFilter Central Server - Installed at NetFilter premises it performs administration and updating databases functions.